Wood Boring Bees

Hello to All, It has been a long time since I have come to you for any help. The forums have changed. I am in need of help with a beautiful wooden bench from Mexico that the back is all hand carved and painted. A few years back when I purchased it from a local nursery, I asked what to paint over the wood to help keep the color from fading and what to do about the feet sitting on cement on the landing outside my front door. I was given expert advise on what to do.

Now I come to you as this year, for the first time, one of those large bees is boring holes in the bottom, having made 5 holes already. I saw sawdust and located the first hole and put pieces of steel wool in it hoping that I had trapped it. No such luck and when my husband turned it over just now, I saw at least 5, maybe one or two more, holes. He sprayed these holes with flying insect spray, but that won't prevent it from boring other holes.

What must we do to keep them from destroying my bench. For now, the holes are on the bottom and placed in a way that they have not come through.